Preheat oven to 400F. Wash and dry the russet potatoes. Pierce several times with a fork, rub with 1 tbsp olive oil, and sprinkle with a pinch of salt. Bake for 60 minutes until tender.
While potatoes bake, prepare the parmesan cream sauce. In a small saucepan, simmer heavy cream over medium heat. Whisk in parmesan cheese until smooth and slightly thickened. Keep warm.
Heat a cast-iron skillet over high heat with 1 tbsp olive oil. Season the beef cubes generously with salt and pepper. Add to the hot skillet in a single layer and sear for 2 minutes per side until browned.
Reduce heat to medium. Add butter and minced garlic to the skillet, stirring continuously for 1 minute until the beef pieces are coated in the garlic butter.
Slice the baked potatoes open and fluff the insides. Divide the garlic butter beef evenly among the potatoes, then generously drizzle the warm parmesan cream sauce over the top before serving.